Clinical relevance of a polymorphism within the ihterleukin-lβ (IL-Lβ) promoter in patients with multiple sclerosis

Cytokines are essential in orchestrating autoimmune inflammatory phenomena typical of multiple sclerosis (MS), a polygenic demyelinating disease of the CNS. As most cytokines, IL-Ib,the prototypical proinflammatory cytokine, is polymorphic. We evaluated the clinical relevance of a restriction polymorphism of its promoter, resulting in two alleles (AI and A2), in 352 MS patients (146 Caucasians and 206 Sardinians) and 210 healthy controls (HC) (126 Caucasians and 82 Sardinians). Genotype frequencies were similar between MS groups and healthy controls (HC). When analysing possible influences of the A1 allele on clinical features of MS, we found A1 significantly and positiveliy associated with relapsing-remitting (RR} VS. primary progressive (p<0.05), and with benign MS (disease duration ) >10 years and EDSS <3) vs. non benign MS (p<0.05) or HC state (p<0.05). The A1 carriage rate (CR) was also higher in the group with benign RR MS (0.63| compared to non benign RR MS patients (0.52). Regression analysis of patients with disease duration >10 years indicated a direct correlation between A1 CR and EDSS (p<0.05}. This study suggests that, IL-Ib alleles do not influence susceptibility to MS. However, the IL-Ib A1 allele may have a modifying role in patients with MS, possibly fostering a RR type and a milder course of disease.